1. Field of the Invention
The present invention relates to a photoelectric conversion device, and particularly relates to a photoelectric conversion device including a thin film semiconductor element and a manufacturing method thereof. In addition, the present invention relates to an electronic device using a photoelectric conversion device.
2. Description of the Related Art
A number of photoelectric conversion devices used for detecting an electromagnetic wave are generally known, for example, a photoelectric conversion device which has sensitivity from ultra-violet rays to infrared rays is referred to as a light sensor in general. A light sensor which has sensitivity to a visible light region with a wavelength of 400 to 700 nm is particularly referred to as a visible light sensor, and a number of visible light sensors are used for devices which need illuminance adjustment, on/off control, or the like depending on a human living environment.
In particular, in a display device, brightness of the periphery of the display device is detected to adjust the display luminance. It is because unnecessary electric power can be reduced by detecting the peripheral brightness and obtaining appropriate display luminance. For example, a light sensor for such adjustment of luminance is used for a cell phone or a personal computer.
In addition, not only peripheral brightness but also luminance of backlight of a display device, particularly, a liquid crystal display device is also detected by a light sensor to adjust luminance of a display screen.
In such a light sensor, a photodiode is used for a sensing part and an output current of the photodiode is amplified in an amplifier circuit. As such an amplifier circuit, for example, a current mirror circuit is used (Patent Document 1).
[Patent Document 1] Patent Document No. 3444093